# Relationship history for MSHA mine 4000020

Current hierarchy: **Vulcan Materials Company → Vulcan Construction Materials, LLC → Columbia Quarry**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **controller_controls_mine:** Legacy Vulcan Corp (Form:Vulcan Materials Co) → Columbia Quarry; 1950-01-01 to 2007-11-15; source msha-controller-operator-history
- **operator_operates_mine:** Columbia Rock Products Corp → Columbia Quarry; 1950-01-01 to 1984-12-30; source msha-controller-operator-history
- **controller_controls_mine:** Harry  Pressnell → Columbia Quarry; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Harry  Pressnell → Columbia Rock Products Corp; 1950-01-01 to 1984-12-30; source msha-controller-operator-history
- **operator_operates_mine:** D & P Materials Inc → Columbia Quarry; 1984-12-31 to 1989-02-28; source msha-controller-operator-history
- **controller_controls_mine:** Morton  Damron → Columbia Quarry; 1984-12-31 to 1989-02-28; source msha-controller-operator-history
- **controller_controls_operator:** Morton  Damron → D & P Materials Inc; 1984-12-31 to 1989-02-28; source msha-controller-operator-history
- **operator_operates_mine:** Columbia Rock Products Corp. → Columbia Quarry; 1989-03-01 to 2004-01-28; source msha-controller-operator-history
- **controller_controls_mine:** Allen  Pressnell → Columbia Quarry; 1989-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Allen  Pressnell → Columbia Rock Products Corp.; 1989-03-01 to 2004-01-28; source msha-controller-operator-history
- **operator_operates_mine:** Vulcan Construction Materials, LLC → Columbia Quarry; 2004-01-29 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Legacy Vulcan Corp (Form:Vulcan Materials Co) → Vulcan Construction Materials, LLC; 2004-01-29 to 2007-11-15; source msha-controller-operator-history
- **controller_controls_mine:** Vulcan Materials Company → Columbia Quarry; 2007-11-16 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Vulcan Materials Company → Vulcan Construction Materials, LLC; 2007-11-16 to current/open; source msha-controller-operator-history